Wrap-around carriers or cartons are commonly used to package beverage containers as well as other types of articles. To form a package the centrally located top panel section of a carrier blank is normally positioned on a group of articles to be packaged and the side panel sections are folded down. Bottom panel flaps at opposite ends of the blank are then folded into place, with one of the flaps partially overlapping the other. Primary locking tabs on one of the flaps are connected to an edge of a primary opening in the other flap, and secondary locking tabs are secured so as to prevent the primary locks from separating. Prior to securing the locks the blank must be tightly drawn about the articles to prevent movement by the articles in the package. This requires the bottom panel flaps to be pulled into final position before the locking tabs can be set into place. Often, the design of the locking mechanism requires this to be accomplished through the use of fingers on the packaging machine which grip and pull the flaps into their final position.
A problem with the type of forming procedure described is that the packaging machines have to be timed and pitched according to the style of carton being run. In other words, the carton tightening fingers must be operated at distance between the center line of adjacent packages, and the speed at which the packages are moving through the machine. Therefore the packaging machine locking device must be reset each time a package is run for articles of different size or configuration.
It would be highly advantageous to be able to run different types of wrap-around cartons on the same packaging machine without having to change the pitch and timing of the locking device on the machine each time. Preferably, the design of the carton panel flaps and the locks themselves should be such that primary and secondary locks are provided.